The effect of OX-LDL and simvastatin on PKC activity and cytosolic free Ca~(2+) in cultured human monocytes / 中国药理学通报

ABSTRACT

AIM To investigate the effect of OX- LDL and HMG-CoA reductase inhibitors simvastatin on PKC activity and cytosolic free Ca2+ in cultured human monocytes. METHOD The activity of PKC was determined by its ability to transfer phosphate fm [32P] ATP to lysine-rich histone and cytosolic free calcium[Ca2+]i was measured by flow cytometric analysis loading with the Ca2+ dye fluo3/Am.RE- SULTS OX-LDL increased PKC total activity in a dose-dependent manner with phase peaking at 12 min, then decreased slowly and maintained for at least 20 min, while OX-LDL induced biphasic [Ca2+ ], responses including the rapid initial transient phase and the sustained phase. Removal of extracellular Ca2+ did not inhibit the rapid initial transient phase of OX-LDL-induced rise. in [ Ca2+ ]i, but abol- abolished the sustained phase of [ Ca2+ ] i response to OX LDL. When simvastatin was added, the activity of PKC was markedly decreased and simvastatin did not impair the initial peak response to OX-LDL but sig- nificantly reduced the subsequent plateau phase. CONCLUSION OX-LDL can significantly activate the activity of PKC and elevate [Ca2+ ]i in monocytes. The rapid initial transient phase was the result of mobilization of [Ca2+ ], fm intracellular pool and sustained phase resulted from the influx of extracellular Ca2+. The inhibition of PKC activity induced by simvastatin may be contribute to the changes of intracellular Ca2+.